Sonika invested an amount of Rs.5800 for 2 years. At what rate of compound interest will she get an amount of Rs.594.50 at the end of 2 years ?

Correct Answer: Rs. 704

Explanation:

We know that,

$$\begin{gathered} S . I . = PTR 100 \\ ? P = S . I x 100 T x R \\ And also , \\ C . I = P 1 + R 100 n - 1 \end{gathered}$$

From given data, P = Rs. 8625

Now, C.I  =  $$\begin{gathered} 8625 1 + 4 100 2 - 1 \\ = 8625 26 25 2 - 1 \\ = 8625 676 625 - 1 \\ = 8625 x 51 625 \\ C . I = Rs . 703 . 80 \end{gathered}$$

Correct Answer: 2.04

Explanation:

C.I. when interest
compounded yearly=rs.[5000*(1+4/100)(1+1/2*4/100)]

= Rs. 5304.

C.I. when interest is
compounded half-yearly=rs.5000(1+2/100)^3

= Rs. 5306.04
Difference = Rs. (5306.04 - 5304) = Rs. 2.04

Correct Answer: Rs. 441

Explanation:

Given principal amount = Rs. 8000

Time = 3yrs

Rate = 5%

C.I for 3 yrs =  $$\begin{gathered} 8000 x 105 100 x 105 100 x 105 100 - 8000 \\ = Rs . 1261 \end{gathered}$$

 

Now, C.I for 2 yrs =  $$\begin{gathered} 8000 x 105 100 x 105 100 \\ = Rs . 820 \end{gathered}$$

 

Hence, the required difference in C.I is 1261 - 820 = Rs. 441

Correct Answer: Rs. 19828.80

Explanation:

Let the sum be Rs. P
P{ 1 + 8 100 2- 1 } = 2828.80

 

It is in the form of   a 2 - b 2 = a + b a - b

 

P(8/100)(2 + 8/100) = 2828.80

 

P = 2828.80 / (0.08)(2.08)

 

= 1360/0.08 = 17000

 

Principal + Interest = Rs. 19828.80

Correct Answer: Rs. 445.95

Explanation:

We know Compound Interest = C.I. = P1+r100t - 1

Here P = 2680, r = 8 and t = 2

C.I. = 26801 + 81002-1= 268027252-12= 26802725+12725-1= 2680 5225×225

= (2680 x 52 x 2)/625

= 445.95

 

Compound Interest = Rs. 445.95

Correct Answer: 4 years

Explanation:

P 1 + 20 100 n > 2P 

 

 

 

Now, (6/5 x 6/5 x 6/5 x 6/5) > 2.

 

 

 

So, n = 4 years.

Correct Answer: 15%

Explanation:

Let the rate be R% p.a. Then,

 

1800 1 + R 100 2 - 1800 - 1800 * R * 2 100 = 405

1800 100 + R 2 10000 - 1 - 2 R 100 = 405

  1800 100 + R 2 - 10000 - 200 R 10000 = 405

?

9 5 * R 2 = 405 ? R 2 = 405 * 5 9 = 225 ? R = 15 
Rate = 15%.

Correct Answer: 5years

Explanation:

Rs.100 invested in compound interest becomes Rs.200 in 5 years.

The amount will double again in another 5 years.

i.e., the amount will become Rs.400 in another 5 years.

So, to earn another Rs.200 interest, it will take another 5 years.

Correct Answer: 1080

Explanation:

Let the sum be Rs. x. Then,

 

  C . I = x * 50 300 * 100 3 - x = 343 x 216 - x = 127 x 216 

 

? 127 x 216 = 1270 

 

x = 2160 

 

Thus, the sum is Rs. 2160

 

  S . I = R s . 2160 * 50 3 * 3 * 1 100 = R s 1080

Correct Answer: Rs.8820

Explanation:

Amount

=Rs.[8000x(1+5/100)²]

= Rs.[8000 x 21/20x21/20]

= Rs.8820.